diff --git a/ci-build.sh b/ci-build.sh
index c9fdcb0e..73a27e73 100755
--- a/ci-build.sh
+++ b/ci-build.sh
@@ -204,6 +204,13 @@ case "$ARCH" in
         ""
         )
         source /etc/profile.d/debuginfod.sh 2>/dev/null || true
+
+        if grep -q 'ID=arch' /etc/os-release 2>/dev/null && [ -f /etc/makepkg.conf ]; then
+            echo "--> [Parity Mode] Simulating Pikaur collision..."
+            set -a
+            source /etc/makepkg.conf
+            set +a
+        fi
         ;;
     darwin*)
         # 4 configurations for parallel CI
diff --git a/configure.ac b/configure.ac
index 35adddb4..6ae0550c 100644
--- a/configure.ac
+++ b/configure.ac
@@ -388,13 +388,12 @@ AC_SUBST([FORKPTY_LIB])
 
 ## Default parameters
 AM_CFLAGS="$AM_CFLAGS -Wall -Wextra -Wformat=2 -Wno-format-zero-length"
-AM_CFLAGS="$AM_CFLAGS -Wno-deprecated-declarations -Wno-unused-parameter -Wno-missing-field-initializers -Wno-cast-function-type"
-AM_CFLAGS="$AM_CFLAGS -Wnull-dereference -Wpointer-arith"
+AM_CFLAGS="$AM_CFLAGS -Wno-deprecated-declarations -Wno-unused-parameter -Wno-missing-field-initializers -Wno-sign-compare -Wno-cast-function-type"
+AM_CFLAGS="$AM_CFLAGS -Wpointer-arith"
 AM_CFLAGS="$AM_CFLAGS -Wimplicit-function-declaration"
 AM_CFLAGS="$AM_CFLAGS -Wundef"
 AM_CFLAGS="$AM_CFLAGS -Wfloat-equal -Wredundant-decls"
 AM_CFLAGS="$AM_CFLAGS -fstack-protector-strong -fno-common"
-AM_CFLAGS="$AM_CFLAGS -D_FORTIFY_SOURCE=2"
 AM_CFLAGS="$AM_CFLAGS -std=gnu99 -ggdb3"
 
 # GCC-specific warnings (not supported by clang) — test each one